Ahearn (Eocene of the United States)

Where: Pennington and Shannon County, South Dakota (43.6° N, 102.5° W: paleocoordinates 44.9° N, 93.6° W)

• coordinate based on political unit

When: Ahearn Member (Chadron Formation), Chadronian (37.2 - 33.9 Ma)

Environment/lithology: terrestrial; lithology not reported

Size class: macrofossils

Primary reference: J. Clark and J. R. Beerbower. 1967. Geology, paleoecology, and paleoclimatology of the Chadron Formation. Fieldiana 5(5):21-74 [J. Alroy/J. Alroy/J. Alroy]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 16885: authorized by John Alroy, entered by John Alroy on 18.02.1993, edited by Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

• dated at 36.3 +/- 0.7, 35.1, and 36.2 Ma: Emry et al. 1987; average is 35.87 (= 36.80) Ma
Reptilia
 Crocodylia - Alligatoridae
Alligator cf. prenasalis Loomis 1904 alligator
 Testudines - Emydidae
Emydidae indet.6 Rafinesque 1815 turtle
"scrap"
 Testudines - Carettochelyidae
Anosteirinae indet.4 Lydekker 1889 turtle
"Pseudanosteira or Anosteira... scrap"
 Testudines - Trionychidae
"Apalone leucopotamica" = Trionyx leucopotamicus4
"Apalone leucopotamica" = Trionyx leucopotamicus4 Cope 1891 softshell turtle
"scrap"
 Squamata -
Peltosaurus sp. Cope 1873 squamates
Mammalia
 Creodonta - Hyaenodontidae
Hyaenodon cf. horridus Leidy 1853 creodont
Hyaenodon cf. montanus Douglass 1902 creodont
 Carnivora - Nimravidae
? Eusmilus sp. Gervais 1876 false sabre-tooth
 Carnivora - Amphicyonidae
"Daphoenocyon minor n. sp." = Brachyrhynchocyon dodgei
"Daphoenocyon minor n. sp." = Brachyrhynchocyon dodgei Scott 1898 bear-dog
 Carnivora - Subparictidae
"Parictis dakotensis" = Subparictis dakotensis2
"Parictis dakotensis" = Subparictis dakotensis2 Clark 1936 carnivoran
SE 1/4 NE 14 NW 1/4 sec 5 T4S R12E, Pennington Co.; same as type locality of P. gilpini
 Carnivora - Ursidae
Parictis parvus n. sp. Clark and Beerbower 1967 bear
from west flank of Quinn Draw, Shannon Co.: see Clark and Guensburg 1972
Parictis gilpini n. sp.2 Clark and Guensburg 1972 bear
Little Corral Draw, Pennington Co.
 Perissodactyla - Equidae
Mesohippus celer, "Mesohippus viejensis" = Mesohippus bairdi, "Mesohippus hypostylus" = Mesohippus bairdi
Mesohippus celer Marsh 1874 anchitheriine horse
"Mesohippus viejensis" = Mesohippus bairdi Leidy 1850 anchitheriine horse
"Mesohippus hypostylus" = Mesohippus bairdi Leidy 1850 anchitheriine horse
 Perissodactyla - Rhinocerotidae
Subhyracodon mitis1 Cope 1875 rhinoceros
Trigonias sp. Lucas 1900 rhinoceros
 Perissodactyla - Hyracodontidae
Hyracodon cf. priscidens Lambe 1905 odd-toed ungulate
probably OK in light of Prothero 1996e
 Perissodactyla - Tapiridae
Colodon occidentalis Leidy 1868 tapir
 Perissodactyla - Brontotheriidae
Brontotheriidae indet.1 Marsh 1873 brontothere
 Artiodactyla - Tylopoda
Tylopoda indet. even-toed ungulate
"camelid new genus and species": may be Montanatylopus; specimens not discussed by Prothero 1986
 Artiodactyla - Camelidae
Poebrotherium sp.1 Leidy 1847 camel
 Artiodactyla - Merycoidodontidae
Merycoidodon sp. Leidy 1848 oreodont
"Big Corral Draw... Pennington Co.:" discussed by Stevens and Stevens 1996
Miniochoerus cf. forsythae8 Schultz and Falkenbach 1968 oreodont
one specimen of "Merycoidodon sp."; said to to "probably" be this species
 Artiodactyla - Anthracotheriidae
Anthracotheriidae indet.5 Leidy 1869 anthracothere
 Artiodactyla - Entelodontidae
Archaeotherium cf. coarctatum Cope 1889 even-toed ungulate
Archaeotherium cf. mortoni Leidy 1850 even-toed ungulate
"Archaeotherium cf. altidens" = Scaptohyus altidens1 Sinclair 1922 even-toed ungulate
 Artiodactyla - Tayassuidae
Perchoerus minor7 Cook 1922 peccary
 Artiodactyla - Protoceratidae
Pseudoprotoceras longinaris3 Cook 1934 protoceratid
 Artiodactyla - Hypertragulidae
Hypertragulidae indet. Cope 1879 ruminant
 Artiodactyla - Agriochoeridae
Agriochoerus cf. antiquus Leidy 1850 agriochoerid
 Rodentia - Ischyromyidae
Ischyromys sp. Leidy 1856 rodent
 Rodentia - Eomyidae
Eomyidae indet. Winge 1887 rodent
Amphibia
 Salientia - Pelobatidae
Eopelobates grandis Zweifel 1956 spadefoot toad